1. Field of the Invention
The present invention relates to a stretchable circuit structure and the fabrication method thereof.
2. Description of Related Art
Along with a developing trend for electronic products to combine light-thin-short-small appearance design with the flexible electronic technology, some flexible electronic products, such as E-paper, flexible display, have be available on the market, wherein the circuits are mostly fabricated on a flexible substrate so as to comply with bending and pulling effects. However, in comparison with a product with a traditional rigid substrate and a better structure strength, the flexible substrate obviously can not support a circuit structure with sufficient structure strength. In particular, when a bending operation or a pulling operation is applied to a flexible electronic product, the circuit located on the flexible substrate may suffer stresses to get damage. Therefore, a circuit employed by a flexible electronic product must be particularly designed in consideration of structure strength issue including altering the material of the circuit so as to meet the reliability requirement on a flexible electronic product.
U.S. Pat. No. 6,743,982 provides a circuit structure fabricated with a polymeric metal material, wherein the different stress gradients of different metal material enables a completed circuit to be bending deformed and to form winding, which make the circuit stretchable. US Patent Application No. 20040192082 provides a fabrication method that a circuit layer is deposited on a flexible substrate with a pull pre-load. Thereafter, the pull load on the substrate is released so as to make the circuit on the flexible substrate become wave-shape and stretchable. In addition, US Patent Application No. 20040243204 provides a circuit directly deposited on a flexible substrate and having wave-shape or serrated-shape so as to take advantage of the figure change of the circuit itself to enhance the horizontal and vertical allowable pull strengths.